Since the advent of rubber tires and pneumatic tires, a multitude of collapsible tire rim wheels have been devised and proposed. The primary object of such collapsible wheels is to provide for collapse and removal of the rim in order to facilitate changing the tire. Typical examples of such prior art inventions are found in U.S. Pat. Nos. 1,009,423; 1,530,865; 1,163,257; and 4,056,285. Such devices do not provide wheels which are collapsible for the purposes of providing a lightweight portable wheel which may be reduced to a small package. Rather they are intended simply for ease in demounting the rim for changing the tire. Not all of the elements of the tire are fully collapsible or adapted for packing in a small space.
In U.S. Pat. No. 1,544,375, Cook describes an expansible rim which includes a fitting for expanding and contracting the rim for removal and replacement of tires. In U.S. Pat. No. 2,170,404 Greaker describes a wheel for artillery vehicles in which the rigid spokes may be dispaced or offset in one direction along the axle against a conical surface to relieve forces on the rim. The rim is then easily removed from the outer end of the spokes for in turn removing and replacing the tire. Thus, the spokes may be offset from a position substantially normal to the axis to a conical offset which permits removal of the tire.
In all the foregoing art, however, a truly portable tire is not contemplated. With the exception of the Greaker reference, only the rim is collapsible and that is for the purpose of changing the tire. In each of the foregoing references a heavy rim is contemplated and a separate tire fitted over the rim. Rigid spokes are required and are generally part of a heavy hub. In Greaker even though the spokes are displaceable along the axle they are nonetheless rigid and not truly collapsible for purposes of portability and packing in a small space.